Sofa



FIG. 1 is a front elevational view of a sofa showing my new design;

FIG. 2 is a side elevational view thereof, the side opposite FIG. 2 being the mirror image of FIG. 2;

FIG. 3 is a rear elevational view thereof; and

FIG. 4 is a top plan view thereof. 

The ornamental design for a sofa, as shown and described. 